Representative Edward J. Markey refused to back down Thursday from comments he made this week that seemed to compare the US Supreme Court’s ruling on campaign finance law to the high court’s 19th-century Dred Scott decision, a notorious pro-slavery ruling.

On Tuesday, at a campaign rally in Pittsfield, the Democrat said that if he is elected to the Senate he will fight for a constitutional amendment to overturn Citizens United, the 2010 case that allowed unlimited third-party spending in political campaigns.

“The whole idea that the Koch brothers, Karl Rove can say we’re coming to Massachusetts, that we’re coming to any state in the union, with unlimited amounts of undisclosed money, is a pollution that must be changed,” Markey said, ­according to a video of the event provided by the National Republican Senatorial Committee.

“The Constitution must be amended,” he added. “The Dred Scott decision had to be ­repealed; we have to repeal ­Citizens United.”

The Dred Scott ruling, in 1857, upheld slavery in US terri­tories and further said that blacks did not have the rights of US citizens. The 13th Amendment of the Constitution, ­adopted in 1865, formally abolished slavery. The 14th Amendment, in 1868, granted citizenship to African-Americans.

Markey made his comments Tuesday afternoon, hours after he met with a group of African- American ministers in Springfield. Several black ministers contacted Thursday said they found the comments inappropriate and off-the-mark, but added that they would not judge Markey solely on that ­remark.

Markey’s opponent in the Democratic primary, Representative Stephen Lynch, condemned the comment, as did Republicans.

In a statement Thursday, Markey repeated his opposition to Citizens United and criticized Republicans for failing to embrace a pact to curb spending from political action committees in the Senate election. He did not disavow his earlier remarks.

“The Supreme Court had the horrific judgment to issue the Dred Scott decision, and people rose up to challenge it,” he said. “Today, we’re faced with another egregious decision that needs overturning, Citizens United. The damage the court ­unleashed by allowing outside money to control elections constitutes a legitimate constitutional crisis.”

The Rev. Eugene F. Rivers III, director of the Ella J. Baker House and cofounder of Boston TenPoint Coalition, said that Markey should sit down with African-American clergy in ­Boston to explain “his somewhat revisionist approach to the Dred Scott case.”

“I do not understand the historiographic or historical analogy,” he said. “That makes no sense to me.”

The Rev. Talbert W. Swan II, president of the Springfield NAACP and one of about 15 to 20 people who met with ­Markey earlier Tuesday, said he agreed with Markey that there were some parallels between the two “horrible” court decisions.

“Dred Scott basically upheld considering people as property and continuing to subjugate them and restrict their rights, while Citizens United did the opposite, by recognizing property as people and giving them rights,” Swan said.

But he added that politicians need to be extremely sensitive about making such a comparison, given the significance of slavery in American history and especially within the African-American community.

“While there are some parallels, I don’t think campaign ­finance can be compared to the subjugation of an entire people,” Swan said.

The Rev. William E. Dickerson II, senior pastor at Greater Love Tabernacle in Dorchester, said Markey probably did not intend to compare slavery with campaign finance, but added that people in the public eye need to be careful about their phrasing.

“We minimize the issue of the Dred Scott decision when we try to juxtapose it” with lesser issues, he said. “In terms of its impact and significance, that should stand alone.”

None of the pastors interviewed thought the comments would damage Markey significantly in the black community, however. They said black clergy are looking for candidates who can show a long-term commitment on significant issues, includ­ing incarceration rates for people of color, urban violence, and education.

Swan said he expects that Markey will garner support from many of the black ministers who met with him, because his stances are in line with those of President Obama, Governor Deval Patrick, and others who have won their support. But like other members of the black clergy, he said he wants to hear from all the candidates, from both political parties, ­before making a commitment.

“I think the day of African-Americans automatically supporting the Democratic candidate are over,” Swan said. “We have a more informed electorate that wants to weigh where the different candidates stand on the issues.”

Dickerson said someone from Lynch’s campaign has previously reached out to request an opportunity to address his church, and he expects other candidates from both parties to do the same. African-American voters, who are overwhelmingly registered as Democrats, could be especially influential in the party’s primary, and Lynch’s campaign was quick to seize on Markey’s comments.

“I don’t think it’s right to compare Citizens United to the Dred Scott decision,” Lynch said in a statement. “Dred Scott kept an entire race of people in bondage and perpetuated the horror of slavery in America. I’m not sure there are any ­Supreme Court decisions that rival Dred Scott in infamy.”

Lynch said he also supports a constitutional amendment to overturn Citizens United.

Republicans tried to cast the comments as evidence that Markey is out of touch. “Agree or disagree with federal campaign finance law, it’s ridiculous and offensive to compare it to the horror of slavery,” said Brad Dayspring, spokesman for the National Republican Senatorial Committee.